Generation of high-quality terahertz OAM mode based on soft-aperture difference frequency generation.

We demonstrate the generation of high-quality tunable terahertz (THz) vortices in an eigenmode by employing soft-aperture difference frequency generation of vortex and Gaussian modes. The generated THz vortex output exhibits a high-quality orbital angular momentum (OAM) mode with a topological charge of ℓ = ±1 in a frequency range of 2-6 THz. The maximum average power of the THz vortex output obtained was ∼3.

Effect of surfactant addition on removal of microbubbles using ultrasound.

It is difficult to control the bubble in a liquid by the external operation, because the behavior of the bubble is controlled in buoyancy and flow of liquid. On the other hand, microbubbles, whose diameter is several decades μm, stably disperse in static liquid because of their small buoyancy and electrical repulsion. When an ultrasound, whose frequency was 2.

Effect of irradiation distance on degradation of phenol using indirect ultrasonic irradiation method.

Ultrasound is used as degradation of hazardous organic compounds. In this study, indirect ultrasonic irradiation method was applied to the degradation process of phenol, the model hazardous organic compound, and the effects of irradiation distance on radical generation and ultrasonic power were investigated. The chemical effect estimated by KI oxidation dosimetry and ultrasonic power measured by calorimetry fluctuated for the irradiation distance, and there was a relationship between the period of the fluctuation of ultrasonic effect and the wavelength of ultrasound.

Agglomeration and rapid ascent of microbubbles by ultrasonic irradiation.

Microbubbles have some different characteristics from conventional bubbles. To apply the useful properties for gas-liquid contact operation in industry, however, a separate technology of microbubbles has to be realized. In this study, promotion of microbubble separation using ultrasound was proposed.